1. Field of the Invention
This invention relates in general to evaporative coolers and more particularly to an evaporative cooler having an improved fan-type air handling mechanism.
2. Description of the Prior Art
For many years, evaporative coolers have been used as an economical way to supply cooled air to commercial and residential buildings.
Briefly, evaporative coolers normally include a four sided cabinet structure having loosely packed wettable fibrous pads, most often of excelsior, mounted in the sides thereof. The bottom of the cabinet serves as a sump, or reservoir, for water which is pumped through a suitable plumbing system to the upper part of the cabinet and is distributed to the tops of the fibrous pads for wetting thereof. The water trickles down through the pads under the influence of gravity and returns to the sump for recirculation. An air handler mechanism is mounted within the cabinet which operates to draw ambient air into the cabinet through the wet fibrous pads so that the air is cooled by the well known evaporation principle. The air handler mechanism is connected to an outlet opening formed in the side of the cabinet so that the evaporatively cooled air is directed exteriorly of the cabinet for delivery either directly to a point of use or to a distribution duct network for delivery to plural points of use.
Evaporative coolers are normally fabricated in either of two basic configurations namely, downdraft and sidedraft models. A downdraft evaporative cooler has its evaporatively cooled air outlet opening formed in the bottom of the cabinet which allows mounting of a wettable fibrous pad in each side of the cabinet. Downdraft evaporative coolers are ideally suited for roof top mounting. A sidedraft evaporative cooler is ideally suited for mounting on a vertical wall for horizontal delivery of the evaporatively cooled air such as through a wall via a hole especially formed for that purpose or through a window. Sidedraft units are configured with their evaporatively cooled air outlet opening in one of the sides of the cabinet with the remaining sides having the fibrous pads mounted therein.
The air handling function in evaporative coolers is accomplished in two ways, either by use of a centrifugal blower assembly or a fan, with engineering considerations, economics, and the like being the factors which determine which of these mechanisms is to be used.
The present invention relates to improvements in fan-type evaporative coolers, therefore, this discussion will be limited to that type of structure. The fan-type air handler mechanism in prior art evaporative coolers typically includes a suitable electric motor mounted within the cooler cabinet so that the motor is in axial alignment with the evaporatively cooled air outlet opening. A multi-blade fan is mounted fast on the motor's shaft with the fan being immediately adjacent the air outlet opening, and a grill or air directing louver assembly is mounted in the air outlet opening.
These fan-type evaporative coolers have been commercially successful for many years and, aside from corrosion and mineral deposition problems which are inherent in all evaporative cooler structures, they have been relatively problem and trouble free.
Recently however, regulatory agencies concerned with consumer product safety have dictated that the grills which are mounted in the air delivery outlet opening of these fan-type evaporative coolers be of a mesh which is small enough to prevent a person's fingers from passing through the grill into the path of the rotating fan. This regulation has resulted in a decrease in the operating efficiency of the evaporative coolers in that grills small enough to keep a child's finger out of the path of the fan cause a restriction, or backpressure, which decreases the air flow through the evaporative cooler. Such a decrease in air flow through the evaporative cooler causes an increased load on the electric fan drive motor which results in increased heating of the motor and higher operating costs. Further, with less air being delivered due to the restricted air flow, less cooling at the point of use results.
Attempts have been made to solve this problem by increasing the size of the electric motor and/or fan and this has not proven to be an efficient method for moving air due to increased initial and operating costs, and is further undesirable due to an increase in noise.
As hereinbefore mentioned, and as is well known in the art, all evaporative coolers, including those of the fan-type, suffer from corrosion and mineral deposition, or scaling, problems. The water used to wet the fibrous pads inherently contains minerals such as calcium chloride and other impurities, and the mineral concentration in the water will increase as a result of the evaporation process. As the water is recirculatingly pumped from the sump or floor pan of the cooler cabinet to the pads, the unevaporated water returns to the sump resulting in a mineral concentration increase in the water reservoir. As the mineral concentration increases, the rate of precipitation will also increase, and ambient air being drawn into the cooler will entrain some of the water and deposit the minerals on every surface and component within the cooler cabinet. The mineral disposition, or scaling, problem is most serious with regard to what it does to the electric motor which drives the air handler. Deposited calcium chloride and other salts are deposited on the wiring, terminals, motor shaft and bearings, and when open or unsealed motors are used, the minerals are deposited on the windings and other internal workings of the motor. These deposited minerals are hygroscopic and have a moist pasty character when the evaporative cooler is operating and will often be in such a state even when the evaporative cooler is not operating due to its inherent tendency to attract moisture from the atmosphere. As a result of the hygroscopic nature of the deposited minerals, shorting out of the motors is an all to frequent occurance.
Therefore, a need exists for a new and improved fan-type evaporative cooler which overcomes some of the problems and shortcomings of the prior art.